According to the Twitter post below from Steven Goff of the Washington Post, Colorado Rapids midfielder Brian Mullan will be suspended for ten games:
Unconfirmed and unofficial but hearing 10 games and 5K fine for Brian Mullan #mlsless than a minute ago via Twitter for BlackBerry® 
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Steven Goff
SoccerInsider
If true, it would equal the longest suspension in MLS history which was levied against the Houston Dynamo's Ricardo Clark for kicking a downed Carlos Ruiz in the chest in retaliation for a foul. The largest fine in league history-$20,000- was charged to Edwin Gorter of the New England Revolution in 1998. Gorter was disciplined for the use of a racial slur against a teammate.
We will have more information once the suspension has been confirmed by the league.